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Strontium isotopes reveal Early Devonian to Middle Triassic carbonate sedimentation in the Sakar-Strandzha Zone, SE Bulgaria

Abstract

We focused on the Sakar-Strandzha Zone (SASTZ) carbonate sequences in Bulgaria, where the Sakar, Subbalkanide and Strandzha Triassic facies types are presented. Strontium isotopic compositions of carbonate samples from the Triassic type section of the Sakar unit confirm an Early-Middle Triassic age of sedimentation consistent with biostratigraphic data, whereas the strontium isotopic compositions of other Sakar-type inferred Triassic sections suggest an Early Permian depositional age. The strontium isotopic compositions of a Strandzha-type Triassic carbonate sample are in agreement with Middle Triassic sedimentation. A few Subbalkanide-type Triassic carbonate samples from the northern and western SASTZ yielded strontium isotopic compositions indicating an Early Devonian sedimentation. The new results indicate late Paleozoic-early Mesozoic sedimentation, and require most of the Subbalkanide-type Triassic and some of the Sakar-type inferred Triassic carbonate sequences in the SASTZ to be revisited.

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Acknowledgements

The study was supported by the Bulgarian National Science Fund project no. DN 04/6. We thank Franz Neubauer and an anonymous reviewer for their critical comments and valuable suggestions, as well as in-depth reading and commenting by the Editor-in-Chief, which altogether helped us to improve the manuscript.

Funding

This study was supported by Bulgarian National Science Fund (Grant No. DN04/6).

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Correspondence to Nikolay Bonev.

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Bonev, N., Chiaradia, M. & Moritz, R. Strontium isotopes reveal Early Devonian to Middle Triassic carbonate sedimentation in the Sakar-Strandzha Zone, SE Bulgaria. Int J Earth Sci (Geol Rundsch) 111, 1307–1314 (2022). https://doi.org/10.1007/s00531-022-02181-6

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Keywords

  • Strontium isotopes
  • Carbonate rocks
  • Sakar-Strandzha Zone
  • Bulgaria